21133409 has 16 divisors (see below), whose sum is σ = 24143616. Its totient is φ = 18326400.

The previous prime is 21133403. The next prime is 21133423. The reversal of 21133409 is 90433112.

It is a cyclic number.

It is not a de Polignac number, because 21133409 - 2⁸ = 21133153 is a prime.

It is a super-2 number, since 2×21133409² = 893241951922562, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21133403) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 20699 + ... + 21695.

It is an arithmetic number, because the mean of its divisors is an integer number (1508976).

Almost surely, 2^21133409 is an apocalyptic number.

It is an amenable number.

21133409 is a deficient number, since it is larger than the sum of its proper divisors (3010207).

21133409 is a wasteful number, since it uses less digits than its factorization.

21133409 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1096.

The product of its (nonzero) digits is 648, while the sum is 23.

The square root of 21133409 is about 4597.1087653002. The cubic root of 21133409 is about 276.4754154768.

The spelling of 21133409 in words is "twenty-one million, one hundred thirty-three thousand, four hundred nine".